Method and apparatus for harvesting crops wherein crops are cleaned at remote site

ABSTRACT

A method and system of harvesting crops involves cutting and threshing the crop, separating graff from straw, and returning the straw to the field. This is carried out in a harvesting unit of the pull type having a graff storage tank. The collected graff is moved to a stationary cleaning mill in a different location by means of a suitable vehicle such as a truck. Storage of the graff prior to cleaning is avoided and the cleaning mill, and the harvesting unit and vehicle.

This application is a continuation of our prior application Ser. No.09/590,362 filed Jun. 9, 2000, now U.S. Pat. No. 6,422,937 issued onJul. 23, 2002.

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

This invention relates to the harvesting of grain and seed crops of thekind that are conventionally harvested by means of a combine harvester.More particularly, the invention relates to systems, methods andapparatus for harvesting such crops.

2. DESCRIPTION OF THE PRIOR ART

The applicant herein has already disclosed a novel method of andapparatus for harvesting grain and seed crops that provide analternative to the use of conventional combine harvesters. In thisregard, reference is made to U.S. Pat. No. 5,794,423 issued on Aug. 18,1998; U.S. Pat. No. 5,795,222 issued on Aug. 18, 1998; and U.S. Pat. No.5,873,226 issued on Feb. 23, 1999; all of these patents having beenassigned to McLeod Harvest Inc. and are referred to collectively in thefollowing description as “the McLeod patents.”

A conventional combine harvester operates by carrying out all of theharvesting steps in the field on a continuous basis. The crop plants arecut, the cut plants are threshed to separate grain (or seeds such aspeas, etc.), chaff and (inevitably) weed seeds from the stalks, thegrain is then cleaned by separating it from the chaff and weed seeds,the grain is delivered to a waiting collection vehicle, and the stalks,chaff and weed seeds are returned to the field. The disadvantages ofthis are that (a) combine harvesters are very expensive to purchase andto operate; (b) they are not very efficient at cleaning the grain, sosome grain is lost and/or further grain cleaning is required; and (c)chaff and weed seeds are returned to the field, so that their economicvalue is lost and weeds proliferate.

The concept underlying the systems disclosed in the above patents isthat, instead of attempting to carry out all of the harvesting steps inthe field, only the step of threshing and removing stalks is carriedout, and the remaining product (a mixture of grain, chaff and weedseeds—referred to by the coined word “graff”) is collected andtransported to a fixed grain cleaning site. The advantage of this isthat the harvesting equipment may be less complicated and expensive thana conventional combine harvester, the cleaning of the grain may becarried out more efficiently at a fixed site, the economic value of thechaff and weed seeds may be realized, and the need for herbicides isreduced (because the weed seeds are collected rather than being returnedto the field).

It has been found that this system is extremely effective, butinconveniences have been encountered in that graff has proven to be adifficult material to handle and process. Since graff contains a largepercentage of chaff, it is bulky for its weight and it is quite fibrousin composition. Unlike grain collected by a combine harvester, graffdoes not easily “flow” from containers and it is difficult to move byconventional means, such as augers, because it bridges or binds withinitself and does not flow internally to replace material that has beenremoved from the bottom of a container or pile of the material. Ingeneral, it can be said that graff tends to pack, clump, bridge,rat-hole and bind, rather than flow smoothly. This causes problems notonly when the graff is stored in silos or the like before it isprocessed, but also causes difficulties of material flow within theharvesting device and transportation vehicles.

Moreover, graff is difficult to store because, if stored in the open, ittends to blow away and also to spoil if it gets wet. However, if storedin a container, it is difficult to remove for the reasons mentionedabove.

Additionally, there is a need to improve the overall efficiency of thesystem generally and to improve the manner in which individualcomponents operate in order to increase the economic competitiveness ofthe system with conventional harvesting systems.

SUMMARY OF THE INVENTION

An object of the invention is to improve the efficiency and to reducethe equipment cost of carrying out a grain harvesting method of the typedisclosed in the patents mentioned above.

Another object of the invention, at least in its preferred forms, is toovercome difficulties caused by the poor flow properties of graff.

Another object of the invention, at least in broader aspects, is tooptimize a grain harvesting system as opposed to a single grainharvesting machine such as a conventional combine harvester.

Another object of the invention is to reduce the operational cost ofcarrying out a grain harvesting method of the type disclosed in thepatents mentioned above.

Another object of the invention, at least in its preferred forms, is toimprove the effectiveness of the harvesting unit used to separate thegraff from the crop stalks in the field.

Another object of the invention, at least in its preferred forms, is toimprove the effectiveness of the grain cleaning mill used to separategrain from the remainder of the graff at a fixed site and to processcrop the residue.

According to one aspect of the invention, there is provided a method ofharvesting and cleaning a plant crop, wherein the crop is cut from afield area and threshed in a mobile harvesting unit to produce stalksthat are returned to the field area and “graff”, a mixture includinggrain, chaff and weed seeds, which is collected within the harvestingunit; the collected graff is transferred periodically from theharvesting unit to at least one vehicle and transported by said at leastone vehicle to a cleaning mill, and the graff is cleaned by the cleaningmill to produce a cleaned grain product and “millings”, a mixtureincluding chaff and weed seeds. To avoid problems caused by the poorflow characteristics and very low density of graff, the method isoperated to avoid storage of the graff prior to cleaning by the cleaningmill.

What we mean by avoiding storage of the graff prior to cleaning is thatthe graff is not transferred to any temporary storage container orstorage pile from the time it is produced by the harvester to the timeit is cleaned by the cleaning mill. The graff is held only in theharvester unit and the vehicle, and is fed immediately into the cleaningmill. Consequently, the use of stationary surge bins and the like at thecleaning mill or other area is specifically avoided. The graff is feddirectly from the harvesting unit to the vehicle, and directly from thevehicle to the a receiving unit for the cleaning mill from which it isfed substantially immediately and completely into the cleaning mill.

Thus, according to another aspect of the present invention, there isprovided a system for harvesting and cleaning a plant crop, whichincludes a harvesting unit for cutting a crop from a field area and forthreshing the cut crop to produce stalks that are returned to the fieldarea and “graff”, a mixture including grain, chaff and weed seeds, whichis collected within the harvesting unit; at least one vehicle forreceiving collected graff from the harvester unit when the harvestingunit is at least partially full, and for transporting the graff to acleaning mill; and a cleaning mill located at a site (yard area) remotefrom the field area, for cleaning the graff to produce a cleaned grainproduct and “millings”, a mixture containing chaff and weed seeds. Thesystem specifically excludes and avoids the use of any device forstorage of the graff prior to cleaning of the graff in the cleaningmill.

According to another aspect of the invention, there is provided astationary cleaning mill for graff, comprising an entrance (usuallylocated at an elevated position) for the graff, screening apparatus forseparating grain from the graff to produce cleaned grain and millings,and separate outlets for the cleaned grain and millings. The cleaningmill includes a receiving unit for the graff for feeding the graff tothe entrance of the graff cleaning mill, the receiving unit being sizedto permit a graff delivery vehicle to drive into the receiving unit totransfer an entire vehicle load of graff to the receiving unit by adirect dumping operation of the entire vehicle load.

In another aspect, the invention provides a stationary cleaning mill forgraff, comprising an entrance (usually located an elevated position) forthe graff, screening apparatus for separating grain from the graff toproduce cleaned grain and millings, and separate outlets for the cleanedgrain and millings. The cleaning mill includes a material-conveying fanat the outlet for the millings, the material-conveying fan impacting themillings to cause at least partial crushing or breaking of weed seeds inthe millings, removing the millings from the cleaning mill, andpropelling the millings through the outlet for the millings.

According to yet another aspect of the invention, there is provided amobile harvesting unit for harvesting graff, including a wheeledharvester body and a harvesting header at the front of the harvesterbody for cutting a crop from a field area, the harvester body containinga threshing unit for the cut crop for separating stalks from graff, adischarge for discharging separated stalks back to the field area, and astorage tank for storage of the separated graff. The harvesting unitincludes an elongated hitching arm having opposite lateral ends forconnection at one end to the harvester body and at an opposite end to arear portion of a propulsion device, the hitching arm having a raisedsection intermediate the opposite ends passing over and clear of theharvesting header.

According to yet another aspect of the invention, there is provided ahitching arm for a graff harvester, comprising a rigid elongated elementhaving two opposite ends for connection, respectively, to the graffharvester and to a propulsion device. The arm has upwardly extendingsections extending from each opposite end towards a centre of thehitching arm, and an elevated centre section.

According to still another aspect of the invention, there is provided areceiving unit for graff, for feeding graff to an elevated entrance of agraff cleaning mill, including a receptacle for graff and a conveyor forraising graff from the receptacle to the elevated entrance. Thereceptacle is sized to permit a graff delivery vehicle to drive into thereceptacle and to deposit an entire vehicle load of graff into thereceptacle by a direct dumping operation.

Preferably, the invention may provide a method of harvesting andcleaning a plant crop, wherein the crop is cut from a field area andthreshed in a mobile harvesting unit to produce stalks that are returnedto the field area and graff, a mixture of threshed grain kernels, chaffand weed seeds, which is collected within the harvesting unit, thecollected graff is transferred to a vehicle when the harvesting unit isfull, the graff is transported by the vehicle to a cleaning mill locatedin a yard area remote from the field area, and the graff is cleanedautomatically by the cleaning mill to produce a cleaned grain productand a mixture of chaff and weed seeds, wherein a capacity of theharvesting unit to hold graff is made the same as or smaller than acapacity of a vehicle used for the delivery, the rate of cleaning of thegraff by the cleaning mill is made the same as or higher than a rate ofgraff output from the field area averaged over several cycles of fillingand emptying the harvesting unit and transfer to the vehicle, and thenumber and speed of operation of the vehicles is made high enough toavoid substantial waiting periods between filling of the harvesting unitwith graff and transfer of the collected graff to the vehicle.

Preferably, the capacity of the harvesting unit is substantially thesame as the capacity of the vehicle, and a single vehicle is providedfor transporting the graff.

It is also preferable that the capacity of the cleaning mill to hold andprocess graff is no less than the capacity of the vehicle to transportgraff from the field area to the cleaning mill, and the rate of cleaningof the graff by the cleaning mill is about the same as the rate of graffoutput from the field area.

In another preferred form, the invention provides a system of harvestingand cleaning a plant crop, which comprises: a harvesting unit forcutting a crop from a field area and threshing the cut crop to producestalks that are returned to the field area and “graff”, a mixture ofgrain, chaff and weed seeds, which is collected within the harvestingunit, a vehicle for receiving collected graff from the harvester unitwhen the harvesting unit is full, and for transporting the graff to acleaning mill; and a cleaning mill located in a yard area remote fromthe field area, for cleaning the graff to produce a cleaned grainproduct and “millings”, a mixture of chaff and weed seeds, wherein acapacity of the harvesting unit to hold graff is made the same as orsmaller than a capacity of a vehicle used for the delivery, a rate ofcleaning of the graff by the cleaning mill is made the same as or higherthan a rate of graff output from the field area averaged over severalcycles of filling and emptying the harvesting unit and transfer to thevehicle, and a number and speed of operation of the vehicles is madehigh enough to avoid substantial waiting periods between filling of theharvesting unit with graff and transfer of the collected graff to thevehicle.

In another preferred aspect, the invention relates to a mobileharvesting unit for harvesting graff, comprising a harvesting header(e.g. a direct-cut or swath pick-up type) at a front of the harvestingunit for removing a crop from a field area, a threshing unit forseparating stalks from a mixture graff, a mixture of grain, chaff andweed seeds, a storage tank for storage of the separated graff, and ahitching arm for connection to a rear portion of a propulsion device,the hitching arm being of inverted generally U-shape to allow attachmentat opposite ends of the arm to the unit and the propulsion device whileextending over the harvesting header.

In the harvesting unit of this kind, the hitching arm preferablysupports and guides a mechanical driveling for transferring mechanicalpower from the propulsion device to the harvesting unit, the drivelineincluding a plurality of rotary shafts joined by constant velocityjoints or U-joints to allow the driveline to adapt to changes ofdirection of the hitching arm. The hitching arm may also be used forguiding and protecting hydraulic tubes for conveying hydraulic fluidunder pressure from the propulsion device to the harvesting unit. Thesetubes may pass through an interior channel in the hitching arm.

In another preferred aspect, the invention relates to a mobileharvesting unit for harvesting graff, comprising a cutting head, athreshing unit for separating stalks from graft, a mixture of grain,chaff and weed seeds, a storage tank positioned above the threshing unitfor temporarily storing graff, an auger bed for transporting graff tocollection areas on opposite lateral sides of the unit, and a pair ofgraff elevators, one on each side of the storage tank, forsimultaneously removing graff from the collection areas of the auger bedand for delivering removed graff to a top of the storage tank.

Further, the invention in another preferred aspect relates to a cleaningmill for graff, comprising a receiving unit for graff sized to allow agraff transportation vehicle to drive at least partially therein fordumping a load of graff, a graff conveyor for feeding graff into themill as a moving matted layer of approximately constant thickness(preferably in the range of 1.5 to 3 inches), and elevators for tiltingthe receiving unit, following removal of the vehicle, to cause the loadof graff to slide to the graff conveyor.

Further, in another preferred aspect, the invention relate to a cleaningmill for graff, comprising an aspirator for blowing air through afalling matted layer of graff to remove chaff and light materialsleaving aspirated graff containing grain kernels and heavy materials, acentrifugal separator for removing the chaff from the air after passingthrough the curtain of graff, a fan and ductwork for recirculating aircontinually through the curtain of graff and through the separator, ascreening unit for separating grain from remaining materials from theaspirated graft, an outlet for the separated grain, a mill for millingthe remaining materials to produce millings, ductwork for circulatingthe millings to the centrifugal separator, an outlet device for removingsolids from the centrifugal separator for discharge from the mill.

It will be appreciated that, in the following discussion, the referenceto “grain kernels” or “grain” as the desired product of the harvestingoperation should be taken to include the grain kernels or seeds of allcrops that are harvestable by conventional combine harvesters, notmerely wheat. Such products include, for example, oats, barley, peas,lentils, rice, soybeans, mustard seed, canola, rapeseed, etc. Theharvesting system of the present invention can be operated with all suchcrops.

Moreover, while the grain kernels are separated from the graff to leavea mixture of chaff, weed seeds and other materials, referred to asmillings, the components of the millings may themselves, if desired, beseparated either during the cleaning of the grain in the cleaning mill,or subsequently. Separate outlets may be provided for the separatecomponents of the millings. Thus, while the claims of this applicationmay refer to an outlet for millings, there may in practice be two ormore outlets for various components of the millings, and the term usedin the claims is intended to cover this eventuality.

It will also be understood that the millings may contain additionalelements such as unthreshed heads, pieces of straw, dust, leaves, andother harvesting residues and debris, and so the term should not belimited merely to a mixture of weed seeds and chaff.

In the following description, numerical values are often expressed bothin metric units and in non-metric units (the latter being shown inbrackets). In the event of any discrepancy, the values expressed innon-metric units should be considered correct.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sketch illustrating the overall harvesting methodaccording to a preferred form of the present invention;

FIG. 2 is a perspective view of a preferred embodiment of a harvestingunit suitable for use in the method of the invention;

FIG. 3 is side view, with internal elements visualized, of the preferredharvesting unit of FIG. 2;

FIG. 3A is a view similar to FIG. 3, showing the threshing mechanism andgraff collection area in isolation;

FIG. 4 is a side view in cross-section of a hitching arm of theharvesting unit of FIGS. 2 and 3;

FIG. 5 is a top plan view of a harvesting unit according to FIG. 2 andFIG. 3 showing the method of attachment to a conventional tractor;

FIG. 6 is a top plan view of an auger bed, shown in isolation from otherequipment, as used in the harvesting unit of FIG. 2 and FIG. 3;

FIGS. 7A, 7B, 7C and 7D are simplified cross-sectional view of theharvesting unit of FIG. 2 and FIG. 3, showing how graff is lifted intoand moved within the graff storage tank;

FIG. 8 is a side elevation of an alternative preferred embodiments ofthe harvesting unit and hitching arm of the present invention attachedto a conventional tractor;

FIG. 8A is an enlarged view, partly in cross-section, of a joint in apower transmission line carried by the hitching arm of FIG. 8;

FIG. 8B is a top plan view of the harvester of FIG. 8 showing ahorizontal section immediately beneath the graff storage tank and strawwalkers, showing the augers used to move the graff and the direction ofgraff flow (indicated by arrows);

FIG. 8C is a top plan view of the harvesting unit of FIG. 8 looking downupon the graff collection tank and showing (by arrows) the direction ofmovement of graff through the tank and removal chute;

FIG. 9 is a perspective view of a preferred embodiment of a cleaningmill suitable for use in the method illustrated in FIG. 1;

FIG. 10 is a perspective view on an enlarged scale of a screening unitforming part of the cleaning mill of FIG. 9;

FIG. 11 is a side elevation of a graff receiving unit and graffconveyor, on an enlarged scale, forming part of the cleaning mill ofFIG. 9, the receiving unit being in the down position ready to receive agraff transportation vehicle;

FIG. 12 is a view similar to FIG. 11, but showing the receiving unit inthe raised position for feeding graff to the graff conveyor;

FIG. 13A is a side elevational view of the aspirator, fan andcentrifugal separator forming a closed graff cleaning circuit andforming part of the apparatus of FIG. 9;

FIG. 13B is a view similar to that of FIG. 13A from the other side;

FIG. 13C is a perspective view of a reel used in the apparatus of FIG.13A and FIG. 13B;

FIG. 13D is a sketch showing a millings discharge pipe having a cyclonedeceleration unit at its free end; and

FIG. 14 is a side elevation of a cleaning mill, graff receiving unit andgraff conveyor according to a second preferred embodiment of the presentinvention showing the graff receiving unit in an upright positioncontaining a transported load of graff; and

FIG. 15 is a top plan view of the cleaning mill (the graff receivingunit and graff conveyor having been omitted) according to FIG. 14.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Harvesting Method

One of the objectives underlying the present invention is to improve theefficiency of the graff harvesting and cleaning system described in theMcLeod patents mentioned above, as well as providing a furtheralternative to the use of conventional combine harvesters for harvestinggrain. The inventors named in the present application has found that oneway of achieving this is to ensure that components of the system aredesigned so that harvested material (the graft) flows constantly andefficiently through the system without avoidable delays. This has theadvantage not only of maximizing operation efficiency, but also ofavoiding the need for temporary storage of graff and thus avoiding theproblems caused by the poor flow properties of graff.

As in the McLeod patents, the components of the system of the presentinvention comprise: (1) a mobile harvesting unit for harvesting thecrop, i.e. for collecting graff and returning stalks to the field; (2) acleaning mill for separating grain kernels from the remainder of thegraff, and preferably for crushing and/or shredding the remainder of thegraff to compact it and to reduce the viability of the weed seeds; and(3) one or more vehicles (normally trucks provided with open truck boxescoverable by a tarpaulin or the like to prevent loss of graff throughblowing) for transporting harvested graff from the harvesting unit tothe cleaning mill.

As already noted, a particular problem encountered in dealing with graffis that, while it is not particularly heavy, it is very bulky comparedto the cleaned grain product delivered from a conventional combineharvester (the amount of graff collected from a given crop area may beas much as four times higher in terms of volume than the amount of graincollected by a combine harvester from the same crop area). Moreover,unlike grain, graff does not flow easily; it tends to pack, clump,bridge, rat-hole and bind, making its transfer within and betweenmechanical equipment very difficult.

In view of the problem of excessive bulk, one might think that asolution would be to provide a harvesting unit with an internal graffcollection container (storage tank) that is as large as possible toavoid the need for frequent stops to discharge the collected graff.However, if this is done, the volume of the collected graff may exceedthe capacity of the transport vehicle (truck) used to transport thegraff to the cleaning mill, resulting in delays and/or the need foradditional vehicles. Similarly, if the amount of graff delivered to thecleaning mill at one time is too large, there may be a build-up oroverflow of collected unprocessed graff, ultimately resulting in atemporary storage or termination of harvesting to allow for the graffbuild-up to be processed.

A preferred solution to this problem is to ensure that the capacities ofthe various components (harvesting unit, vehicle, cleaning mill) arematched to allow an even and continuous flow of graff through the systemto avoid the need for temporary storage of the graff before it isprocessed. Consequently, the graff-holding capacity of the harvestingunit should preferably be as large as possible, but no larger than thecapacity of a vehicle used to transport the graff to the cleaning mill,and the throughput of the cleaning mill should preferably be such thatit may handle a volume of graff at least as great as the graff holdingcapacity of a vehicle used to transport the graff in the vehicleturnaround time (the time between successive deliveries of graff fromthe harvesting unit to the cleaning mill).

This is illustrated schematically in FIG. 1 of the accompanyingdrawings. The drawing is a plan view representing in a very general waya field area 10, a road (or track) system 11 and a yard area 12. Aharvesting unit 15 (graff harvester), pulled by a conventional tractor16, harvests a crop from the field area 10, returns stalks to the landand collects graff (threshed grain kernels, chaff, weed seeds, smallbits of straw, etc.) inside the harvesting unit 15 in an internalcontainer (storage tank) until the container is full. The harvestingunit 15 then stops and unloads the collected graff into a grafftransport vehicle 17 (generally a standard dump truck with anopen-topped truck box and an openable rear silage gate) which, whenfull, transports the collected graff 18 to a cleaning mill 20 located inthe yard area 12. Here, the vehicle 17 dumps the graff 18 through theentire rear gate into a graff receiving unit 21 of the cleaning mill 20and returns (as shown at 17′) to the field area to repeat the cycle. Thecapacity of the graff receiving unit 21 should be at least as large asthe carrying capacity of the vehicle 17 so that the vehicle may unloadfully immediately upon arrival at the cleaning mill so that it is notdelayed. If the cleaning mill 20 is intended to process the graff fromseveral harvester units at the same time, then the capacity of thecleaning mill must be increased correspondingly. The graff 18 depositedin the receiving unit 21 of the cleaning mill passes immediately throughthe cleaning mill and is separated into cleaned grain 25 and millings 26(a mixture of smaller grain kernels, weed seeds, chaff, and small bitsof straw, etc.) that have been subjected to milling.

The harvesting unit 15 has an internal graff storage capacity thatshould be approximately the same as, or at least no larger than, thecapacity of the vehicle 17 so that the internal container of theharvesting unit, when full, may be emptied completely into the truck boxof a single vehicle 17. This may be done by stopping the harvesting unitat a waiting truck, or by emptying the harvesting unit into a movingtruck as both continue to move (with or without further harvesting).More than one vehicle may be provided, depending on the distance of thefield area from the yard area 12, and the rate of operation of theharvesting unit 15. Ideally, there should be a waiting vehicle 17whenever the harvesting unit 15 is filled and is consequently requiredto stop. For greatest economy of operation, only a single vehicle 17 isrequired to operate the method continuously, which means that the timerequired to fill the container of the harvesting unit with harvestedgraff should be approximately the same as the time for transport,dumping and return of the single vehicle 17.

This may be expressed in another way. Although the harvesting unit 15harvests (collects and delivers) the graff on a batch basis, it will, onaverage, have a rate of graff delivery that can be expressed in units ofweight or volume per unit time. The rate of graff harvesting by theharvesting unit 15 should, for the most effective and efficientoperation, be essentially the same as the average rate of transport ofthe graff by the vehicle 17 from the field area 10 to the yard area 12.

At the yard area 12, the cleaning mill 20 is capable of processing graffat a certain speed when operating continuously. This can also beexpressed in terms of units of weight or volume per unit time. Forefficient and effective operation, the speed of processing of the graffshould be no slower than the average rate of graff delivery by thevehicle 17, and no slower than the rate of graff harvesting by theharvesting unit 15. This ensures that the various pieces of equipment(harvesting unit, cleaning mill and delivery trucks) all work as anintegrated system.

Ideally, therefore, in this system, the rate limiting step should be theharvesting of the crop by the harvesting unit 15. That is to say, thecrop should be collected, transported and processed as quickly as thecrop can be cut and threshed (stalks removed) by the harvesting unit 15.This means that, if the field area 10 is physically close to the yardarea 12, it may be adequate to have a single vehicle 17 because it mayhave the time to transport, dump and return between each completion of afilling cycle of the harvesting unit. This is the ideal situation.Obviously, from time to time, the ideal arrangement will break down, butthe system should be designed to allow such efficient operation to bethe norm. As the distance from the field area to the yard areaincreases, more vehicles may be provided. However, as the separation ofthe field area from the yard area increases, there will come a time whenit is too expensive or impossible to provide enough vehicles 17 tomaintain the required minimum rate of collection and delivery of thegraff. Often this physical separation limit is found to be in the orderof 6 km. On the other hand, the physical separation of the field area 10and the yard area 12 should have no significant effect on the speed ofthroughput of the cleaning mill because this should always be the sameas, or higher than, the rate of crop cutting and graff collection by theharvesting unit, or several harvesting units if the mill is intended toservice several such units. The relative capacities and throughputs ofthe harvesting unit 15, the vehicle(s) 17 and the mill 20 should bedesigned and utilized to ensure that this is so. Trucks of the typenormally employed for hauling grain and the like usually have a capacityof about 21 m³ (750 cubic feet), so the storage capacity of theharvesting unit 15 and the capacity of the graff receiving unit 21should preferably be about the same.

While this optional organization of the entire system is desirable, itwould still provide problems if carried out with equipment basically asshown in the McLeod patents. The reason for this is best described withreference to FIG. 7 of U.S. Pat. No. 5,795,222, which is one of theMcLeod patents. This drawing shows a grain truck 20 having raised sides21 discharging graff into a hopper 23 through a small discharge portprovided at the lower central part of the read raised side of the truck.The hopper is then emptied by a large grain auger 22 into one of severalsurge storage bins 24 provided for temporary storage. A further auger 26then transfers graff at a constant rate from one of the bins 24 to theupper entrance 54 of the yard plant (cleaning mill) 48. However, becauseof the poor flow properties of the graff, it is difficult to dischargethe material from the truck through the small discharge port in the reartailgate of the truck, and difficult to get the graff to flow from thelower conical ends of the surge storage bins. This createsinefficiencies and difficulties that can cause delays in the cleaning ofthe graff while attempts are made to cause the graff to flow properlyagain.

Solutions to this problem, at least in its most preferred forms of thepresent invention, make use of ways of causing graff to flow that havebeen devised by the inventors. The inventors have observed that graffcan be caused to flow without difficulty in the following ways:

1) Graff can be caused to slide bodily or tumble down a slope (or chute)inclined at a suitable downward angle, provided that it is not impededin any way, e.g. by inwardly tapering or inwardly stepped walls providedat the lateral sides of the sloped surface or chute. This avoids theproblem encountered when a delivery truck of the type shown in theMcLeod patents is provided, i.e. a truck having a small opening ordelivery port provided in the tailgate (which is typical of graindelivery trucks). The tailgate impedes the sliding or tumbling action ofthe graff and provides a “choke point” that impedes smooth graff flow.

2) A quantity of graff can be removed from the bottom of a pile ofgraff, or a container (e.g. a silo) full of graff, provided thatessentially the entire lowermost layer (or an inner layer) of the graffis removed all at one time, rather than just a part of the graff fromthe lowermost layer (or any inner layer) as has been doneconventionally. This can be achieved by moving a conveyor surface or aseries of elongated transverse elements (rakes or slats) beneath thepile or contained body of graff, while preferably maintaining theremainder of the body of graff essentially stationary in some way. Ifessentially the entire lowermost layer of the graff is removed, theremainder of the graff can move downwardly without binding or bridging.If it is desirable to prevent the remainder of the graff from moving asthe lowermost layer is withdrawn (which is the case if a constant supplyof graff is to be delivered to a piece of equipment, such as thecleaning mill), the remainder of the graff may be confined within acontainer or behind a retaining wall, or the body of graff may besupported on an upwardly sloping surface so that the weight of the bodyof graff prevents it from following the movement of the removed layer.

3) Graff can be caused or “encouraged” to flow bodily from one point A,e.g. a point of delivery within a container, to another point B bymoving an upper layer of a body of graff from point A towards point B.This is best used in conjunction with 2), i.e. the moving of a lowerlayer of material from point A to point B (without of course attemptingto prevent the movement of the body of graff as is done in some forms of2). This can be done, for example, by providing augers at an upper levelof the body of graff, and is particularly useful within a graffharvesting unit where graff is collected a the front of a container andhas to be moved to an outlet region or well at the back of thecontainer.

4) Graff can be conveyed in a current of air of suitable volume andvelocity, but this may cause some separation of the components of thegraff. However, such separation is desired in certain parts of thesystem, e.g. in the cleaning mill, so movement of graff in this waytends to be confined to such system parts.

5) Graff can, of course, be moved bodily as a single mass, e.g. on ahorizontal moving surface (e.g. a conveyor). This is useful, forexample, for emptying graff from a rear well of a harvester unit, or thelike.

A practical application of these observations has already been suggestedin FIG. 1 of the present application in that the cleaning mill 20 isprovided with an integral graff receiving unit 21. This is sized toreceive the entire contents of a delivery truck, which can consequentlydump its entire load of graff through its open tailgate (which may behinged at the top or bottom to allow it to be swung out of the way). Aswill be apparent from the following description of preferred versions ofthe cleaning mill described below, the receiving unit is speciallydesigned to raise the deposited graff to an elevated entrance of thecleaning mill without encountering problems caused by the poor flowcharacteristics of the graff.

Thus, an important aspect of the present invention is to avoid the needfor temporary storage of the graff by allowing for a full load of grafffrom at least one delivery vehicle to be delivered at once to a graffreceiving unit of a cleaning mill, which unit can then deliver a regularsupply of the graff to an elevated input opening of a cleaning mill. Ifthis is done, and if the rate of cleaning of the graff in the cleaningmill is sufficiently rapid, the graff may be transferred from theharvesting unit, directly to the delivery vehicle and then directly tothe cleaning mill without any intermediate storage of any kind, thusavoiding problems encountered with the use of conventional storage silosand the like. Temporary storage may of course be provided by thedelivery vehicles themselves, in that if the harvesting rate were toexceed the cleaning rate temporarily, the temporary excess of graffcould be held in a sufficient number of delivery vehicles, if needed,and provided such vehicles were available. Clearly this is to be avoidedif possible, but could provide a temporary solution to overflowproblems.

Another important aspect involves the design of the harvesting unit tomake best use of the principles of graff flow described above.

Yet another important aspect of the invention involves the design of thecleaning mill that makes efficient use of movement and separation ofgraff, at least in part by the use of air currents.

Yet another important aspect of the invention involves the design of theharvester unit that allows it to be towed by a conventional vehicle,e.g. a tractor. While this has nothing to do with the flow properties ofgraff itself, it is important for the overall economy of the presentinvention as such vehicles tend to be less expensive to manufacture andto operate. A special hitching arm has been developed for this purpose.

With these basic concepts in mind, a description of preferredembodiments of the novel components of the graff harvesting system ofthe invention will be provided below.

Improved Graff-Harvesting Harvesting Unit

For even greater efficiency and effectiveness of harvesting, improvedharvesting units have been developed according to the present invention.These harvesting units may be used in the harvesting method indicatedabove or in other harvesting methods, e.g. as disclosed in U.S. Pat. No.5,873,226.

Various graff-harvesting harvesting units are disclosed in U.S. Pat. No.5,794,423. These harvesting units are effective, but they are expensiveto manufacture and can be cumbersome and difficult to operate. Moreover,because of the difficulties in making graff flow evenly, the materialflow through the known harvesting units may not always be optimum. Thepreferred harvesting unit of the present invention overcomes theseproblems to a desirable extent.

Farmers in recent years have become used to self-propelled harvestingunits, such as conventional combine harvesters. Several of theharvesting units disclosed in U.S. Pat. No. 5,794,423 are of theself-propelled kind. However, the required motor, driving controls andsteering mechanisms add considerably to the cost of such vehicles. U.S.Pat. No. 5,794,423 also discloses non-powered (pull-type) harvestingunits (see, for example, FIGS. 4 to 10 of the patent), but these are ofthe “wrap-around” kind, i.e. the harvesting header is positioned infront of a propulsion unit (tractor), while the remainder of theharvesting unit is positioned to the side or rear of the propulsionunit. This leads to a mechanically complicated, cumbersome and expensivedesigns.

The harvesting unit of the present invention is based in part on theconcept of providing a pull-type unit for cost-reduction (most farmersalready have their own tractors or other suitable propulsion units)while avoiding the complexity of the wrap-around design by towing theharvesting unit at the rear of the propulsion unit. However, thiscreates a problem in that, if the harvesting unit is towed behind atractor, there is difficulty in providing a suitable means of attachmentbetween the two since the harvesting header (particularly a direct-cutheader) is necessarily positioned immediately behind the tractor hitchpoint, making a conventional tow bar impossible to use and blockingaccess to the tractor's mechanical and hydraulic power supplies. Theheader also has a cutter bar that must be raised, and this imposes afurther constraint on any towing system. This difficulty has beenovercome according to the present invention by providing a harvestingunit having a novel hitching arm.

A first preferred embodiment of the improved harvesting unit 15 is shownin perspective view in FIG. 2 of the accompanying drawings. As shown,the harvesting unit 15 comprises a harvesting header 30, that may be ofeither the direct-cut type (e.g. a conventional header, normally 7.3 to9 m (24 to 30 feet wide)) or a swath pick-up header (normally 4.25 m (14feet) wide). A crop feeder housing 31, e.g. a chain feeder, feeds thecut crop rearwardly to the harvester body containing the unit's internalthreshing mechanism, described in more detail later, where the cut cropis separated into stalks (which are returned to the field as straw) andgraff (a mixture of grain, chaff and weed seeds, etc.). The body of theharvester unit also contains a graff holding container or tank 33 towhich graff is transferred after being collected from the threshingmechanism. When the tank 33 is full, the unit 15 is stopped (or unloadedon-the-move), and the graff is transferred to a transport vehicle 17(not shown in this view, but see FIG. 1) via an unloading auger 34. Theharvesting unit 15 is pulled on unpowered wheels 32 by a conventionaltractor 16 (not shown in this view, but see FIGS. 1 and 3) via ahitching arm 35 that not only acts as a tow bar, but also suppliesmechanical and hydraulic or pneumatic power to the harvesting unit 15from the tractor and provides a steering function.

In the harvesting unit of the invention, at least in preferred forms,several factors combine to make the use of the illustrated hitching armpossible. Unlike a regular combine harvester, the harvesting unit doesnot contain a grain cleaning apparatus (because it is intended toharvest graff), which means that the threshing cylinder 30 may bepositioned closer to the ground. The grain feeder housing 31 from thecutter head to the threshing cylinder may also be made quite short as aresult (e.g. about 1.2 m (four feet)), and this allows the harvester tobe located closer to the tractor, and means that the cutter head doesnot have to be raised very much in the stowed condition. In consequence,the hitching arm 35 may be quite short and the cutter head 30 easilyfits within the “crook” of the hitching arm in the raised condition.

In a first embodiment, the hitching arm 35 has a closed-in hollowtubular design and, in side view, as best shown in FIG. 3, it has acentrally-raised shape (referred to for convenience in the following asan “inverted U-shape”, although it is realized that this is a very loosedescription —a more accurate description would be that the hitching armis elongate with two opposite ends; the arm ramps or rises upwardly fromeach end towards the centre of the arm, and the arm has a short,elevated, generally horizontal section between the ramped or raisedsections at in the middle of the arm). The inverted U-shape allows thecrook C (upward bend) of the hitching arm to extend over the top of theharvesting header 30, with enough clearance to allow the header to beraised to the elevated (stowed) position shown in FIG. 3. This generallymeans that the crook C, at its highest point, must be elevated by adistance of at least 3 m (10 feet) from the ground. The length of thehitching arm 35 must also be suitable to prevent it fouling theharvesting header 30 during normal harvesting, even when the harvestingunit 15 is steered out of direct alignment with the tractor 16 (as willbe explained later). This usually means that the hitching arm mustproject horizontally by at least about 6.5 m (21 feet). However, thehitching arm should preferably be no longer than necessary to achievethis objective in order to minimize turning moments (that may overwhelmthe steering mechanism of the tractor if they become too great) when thehitching arm is moved to one side of the tractor or the other. Forcomparison, a hitch that would have to be used for a pull-type combineharvester would have to be longer and stronger, i.e. at least 10 m (33feet) in length, because of the added weight of the combine. This makesit extremely difficult or impossible to control side forces in anon-aligned cutting operation. The maneuverability would therefore belost with such a machine.

Since the hitching arm must pull quite a heavy load (the harvesting unitplus harvested graff), and since it is of inverted approximately U-shapeas shown, forces encountered during harvesting will tend to pull theends 37 and 38 of the hitching arm towards or away from each other. Thehitching arm should therefore be made sufficiently strong and rigid thatsignificant flexing of this kind is prevented. In the illustratedembodiment, the hitching arm is made of three main tubular elements ofsquare cross-section, 36, 39 and 40, that are welded together at theirinterconnecting joints 41 and 42. A heavy gauge steel box constructionis suitable for this purpose.

The hitching arm 35 is shown in isolation and in longitudinalcross-section in FIG. 4. The interior 44 of the hitching arm 35 forms anenclosed channel which may be used, if desired, to accommodate hydraulicand electrical lines (not shown) extending between the tractor and theharvesting unit. Generally, the hydraulic system includes threehydraulic sets, one for pivoting the header 30, one for turning theheader, and the third for raising the header. The hydraulic cylinder 69used for raising and lowering the harvester head is visible in FIG. 3.

The top edge of the arm is used for guiding a mechanical driveline 45that conveys rotary motion from the tractor's mechanical drive to theharvesting unit where it is used to drive the harvesting header 30 andother components. The driveline consists of several straight shafts 46,47, 48, 49, 50 interconnected at their ends by means of constantvelocity joints 51, 52, 53, 54 and 55. Alternatively, the joints may beinterlaced pairs of U-joints. The ends of the driveline may also includeconstant velocity joints 56, 57 for connection to the mechanism of theharvesting unit and the tractor, respectively. Suitable bearings 58, 59,60, 61, 62, 63, 64, 65 are provided on the upper surface of the hitchingarm to secure the driveline and to ensure that the shafts rotatesmoothly. The constant velocity joints employed for this purpose arepreferably capable of operating at angles up to 17° and of handlingpower transmission of up to 150 kW (200 hp). The use of constantvelocity joints in the driveline not only means that the driveline mayfollow the inverted U-shape of the hitching arm 35, but also (because ofthe constant velocity joints 56, 57 at the extreme ends of thedriveline) makes it possible that the hitch arm may be moved out ofdirect alignment with the tractor or the harvesting unit withoutdamaging the mechanism.

The driveline may be enclosed by an elongated cover 68 (shown in part inFIG. 2) in the form of an inverted channel section that fits over theupper edge of the hitching arm.

As shown in FIG. 5, the hitching arm 35 is connected to a drawbar 70 ofthe tractor 16 via a conventional hitch 71. At the opposite end, thehitching arm 35 is connected to the harvester unit 15 via a“hydra-swing” hitch, which includes a pair of hydraulic cylinders 72 and73, attached to the body of the harvester unit 15, that allow thehitching arm 35 to be kept in direct alignment with the tractor 16, ormoved to one side or the other, as shown. This sideways movement, whichcan be controlled by the operator of the tractor, allows the tractoritself to remain largely clear of the unharvested crop, and allows theharvesting unit to be swung from one side of the tractor to the other tofacilitate back-and-forth harvesting of the crop. On the other hand, bypositioning the harvesting unit directly in line with the tractor, theoverall width of the equipment may be minimized (for passing throughgates, and the like).

At its opposite end, the hitching arm 35 is connected to a frame element74 of the harvesting unit for rotation about a generally vertical axisby means of a vertical pivots 75 (see FIG. 2). This allows theharvesting unit 15 to remain in a forward-facing direction, i.e. facingin the same direction as the tractor, when moved to one side or theother out of direct rearward alignment with the tractor. The unpoweredwheels 32 on which the harvesting unit 15 rides are not steerable, andthese wheels tend to keep the harvesting unit moving in the samedirection as the tractor, even when the harvesting unit is moved to oneside of the tractor or the other.

As will be appreciated, the tractor 16 both powers and maneuvers theharvesting unit 15. For most applications, a standard 125 kW (165 horsepower (hp)) tractor with a 95 kW (125 hp) power take off (PTO) withthree hydraulic couplings and suitable transmission speeds will besuitable to operate the harvesting unit 15.

As mentioned earlier, graff has proven to be an extremely difficultmaterial to handle because it does not flow easily and because it isbulky and is produced in large amounts. The threshing and storagemechanism of the illustrated harvesting unit 15 is intended to overcomethe difficulty of collecting and processing of graff.

As shown in FIG. 3, a chain-type crop feeder housing 31 conveys cut cropmaterial into the interior of the harvesting unit 15 where the cropmaterial encounters a rotating threshing cylinder 77 and a perforatedconcave 78 that, in conjunction with a rear flanged beater roll 79,subject the crop material to a severe threshing action. The separatedgrain, chaff and weed seeds (i.e. graff) fall through the perforatedconcave 78 and collect on an auger bed 80, i.e. an inner flat surface ofthe harvesting unit beneath the concave provided with several narrowaugers extending front to back. The rest of the crop (stalks andremaining grain, etc.) is then passed from the cylinder 77 to anarrangement of straw walkers 82 which separate any remaining graff fromthe stalks. The graff separated in this way also falls onto the augerbed 80. In the harvester unit 15 of the present invention, the feederhouse 31 and straw walkers 82 may be made considerably shorter thanthose used in a conventional combine harvester (e.g. only 1.2 m (4 feet)long for the feeder house, and 1.8 m (6 feet) long for the strawwalkers, as opposed to 3 m (10 feet) in a combine harvester). Thisallows a more compact unit to be constructed, and the short feederhousing 31 allows the cutter bar of the header to fit under the crook Cof the hitching arm when in the raised position. The threshing cylinder77 is also very low, i.e. much closer to the crop than in conventionalharvester designs. This allows the hitching arm 15 to be made quiteshort (e.g. 6.5 m (21 feet)). The shorter length makes possible theunique shape of the hitching arm and, in turn, the unique shape makes itpossible for the header to be raised and lowered inside the crook of thehitching arm.

The stalks are moved by the straw walkers to the rear of the harvestingunit 15, where they are discharged onto the ground through a dischargeopening 83 either as a swath or as small pieces formed when the stalksencounter an optional straw chopper/spreader 84. As noted, the graffseparated by the straw walkers 82 falls through the straw walkers to thebed 80 of the harvesting unit.

The threshing and graff collection section of the harvester unit 15 isshown in isolation and increased size in FIG. 3A, in particular showingthe various pulleys and drive belts and chains. The feeder of the feederhousing 31 is driven by feeder drive belt 180, and the cylinder 77 isdriven by cylinder drive belt 181. Element 182 is a variable drive beltdriven by the main pulley 183. The beater 79 is driven by a beater drivebelt 184, and chopper 84 is driven by chopper drive belt 185. Asecondary counter shaft 186 is driven by a secondary shaft drive belt187. The straw walkers 82 and auger bed 80 are driven by drive belt 188.Element 189 is a conveyor drive chain.

The auger bed 80 is shown in plan view of FIG. 6 in isolation from theother elements of the harvesting unit. The bed 80 slopes upwardlyslightly from front to rear, but the graff, as it collects, is movedfrom below towards the rear of the bed by a set of several rotatingaugers 84 provided just above the surface of the bed 80 and orientatedin parallel from the front of the bed to the back and across the entirewidth of the bed. The graff is thus moved bodily towards the rear andencounters a transverse channel 85 containing a pair of coaxial crossaugers 86, 87 that move the graff in opposite outward directions shownby arrows A and B towards vertical paddle elevators 88, 89. The storagetank 33 of the harvesting unit 15 (see FIG. 2) is positioned immediatelyabove the collection bed 80 with enough vertical clearance for theaugers 84 and the collected graff.

It is to be noted that, unlike many combine harvesters, the harvestingunit 15 lacks grain cleaning apparatus and a mechanism for returningunthreshed heads to the threshing cylinder. This makes it possible todesign a harvesting unit having a low profile because the storage tank33 may sit low over the auger bed 80, and it also results in a powersaving since material is not being recirculated through the threshingmechanism. This further simplifies the harvesting unit of the presentinvention and makes it mechanically more reliable than a conventionalcombine harvester. In the apparatus of the invention, unthreshed headsare collected with the graff and become part of the millings, asdescribed later.

As noted, the graff from the auger bed 80 is elevated to the height ofthe top of the storage tank 33 by a pair of paddle elevators 88 and 89(see FIG. 3 and FIG. 6) for the graff located at the ends of the trough85 on each side of the storage tank 33. FIGS. 7A, 7B, 7C and 7C arediagrams showing how the graff is raised into the tank 33, moved thereinand removed therefrom. As shown in FIGS. 7A and 7B, the graff elevators88 and 89 are positioned on the outside of the unit at their bottom endsand they extend upwardly and forwardly. The fact that two elevators 88and 89 are provided means that a large volume of graff from thecollection bed 80 can be accommodated at opposite sides of the tank,ensuring a regular flow of graff from the collection bed and into thestorage tank at opposite sides, as shown by the arrows in FIG. 7A. At apoint midway between the lower and upper ends, the elevators pass insidethe tank 33, the entrance areas being shown by shading in the drawing.The elevators discharge within the tank 33 at the upper front end. Apair of inwardly-directed augers 81 move the graff to the middle of thetank where another auger 90 is provided to help distribute the materialto the rear.

FIG. 7C shows the inside of the storage tank 33 at a point behind theelevators 88, 89. The tank has a unique shape designed to minimizeproblems caused by the poor ability of graff to flow. Various augers areprovided to keep the graff moving as required within the tank. The tankis provided with a horizontal leveling auger 90 at the top to move thegraff backwards and to prevent the formation of a central peak. A pairof rotating agitators 91, 92 are provided lower in the tank to helpprevent bridging within the body of graff. These agitators are generallyhorizontal but slope slightly upwardly towards the rear as shown in FIG.3. At the bottorn of the tank 33, a pair of delivery augers 94, 95 areprovided to move the bulk of the graff rearwards towards a well 96 (seeFIG. 7D), i.e. a deeper section of the tank, formed at the rear of thetank (see FIG. 3). The lower wall 190 of the tank 33 is in the form ofan inverted V so that the graff is directed toward transport augers 94and 95. The well 96 forms the lowest collection point for the graff andis thus the last section of the tank to be emptied by an unloading auger34, the bottom end of which is positioned at the bottom of the well 96.The auger 34 is actually made up of two co-operating augers, i.e. avertical auger positioned in the well 96 that lifts the graff out of thewell 96 and a horizontal auger that moves the graff to downward facing,preferably flexible, delivery spout 97. The well 96 forms a hopper whichcontains an exposed inclined section of flighting 99 which draws graffinto the vertical, then horizontal, sections of the unloading auger. Theunloading auger may be centred along the top of the storage tank 33during harvesting, and may be swung to either side or to the rear fordischarge of the graff into a waiting vehicle 17. The unloading augersare preferably of large diameter compared to those for unloading grainfrom combine harvesters. For example, the vertical auger may have adiameter of 41 cm (16 inches) or more and the horizontal auger may havea diameter of 35.5 cm (14 inches) or more. This allows for a very rapidemptying of the tank, i.e. in the region of three minutes.

All of the various augers and agitators are driven by mechanicaltransmissions (e.g. belts and pulleys) taking power from the rotatingshaft carried by the hitching arm 35.

The storage tank 33, which is preferably of approximately 21 m3 (750cubic feet) in capacity (at least twice the size of the collection binof the largest conventional combine harvester) and (as noted above)preferably has the same size as a truck box of the vehicle 17, ispreferably provided with a particular shape that facilitates the storageand movement of the graff. As shown in FIGS. 7A, 7B, 7C and 7D, thefront wall 27 and lower parts of the side walls 28, 29 of the tank slopeinwardly from the lop to the bottom. The angle of slope is preferablymade at least 50° relative to the horizontal, so that the graff slidestowards the bottom of the tank and does not become trapped at the baseof the front and side walls in the form of stagnant piles. This featuremakes use of the observed ability of graff to slide freely down a slopehaving a suitable angle of inclination. The sloping front wall 27 alsoallows the tank to clear the hitching arm 35 and allows better weightdistribution.

Although the storage tank 33 is designed to hold a substantial amount ofgraff, the low density of this material means that the tank does nothave to be unusually strong, so there is no need for cross-bracing ofthe walls, or the like. In fact, the sculptured (tapering) shape of thetank increases its structural strength relative to a rectangular tank ofthe same capacity.

The tank preferably has an open hatch 98 (FIG. 7C) on the top surfacethat may be covered when desired by a roll-back tarpaulin (not shown) orthe like. This allows access to the interior of the tank for maintenanceand to clear blockages.

It has been found advantageous to coat the inside of the tank 33 andauger chutes with a paint that forms a low friction surface in order tominimize binding of the graff at the sides of the tank. Preferably, thepaint should provide a surface having a co-efficient of friction of lessthan about 0.45. Paint containing powdered graphite (e.g. paint sold byAcu Mech Sys Enterprises Ltd., under the trademark SLIP-PLATE®) isparticularly effective in this way.

FIG. 8 is a side view of an alternative preferred embodiment of theharvesting unit and hitching arm of the present invention. In thedescription of this embodiment, elements that are identical orequivalent to those of the previous embodiment are identified by thesame reference number with an added prime (e.g. 15 becomes 15′).

It will first of all be noted from FIG. 8 that the hitching arm 35′ ismade up of four sections rather than three, these sections being 36′,39′, 40′ and an additional vertical section 39 a at the tractor end ofthe hitching arm. The presence of the additional section gives the arm agreater approximation to the inverted U-shape mentioned earlier andprovides greater “headroom” C′ above the harvesting header 30′ to allowthe header to be raised fully to the inactive position, and also allowsmore room for the harvesting header in the operational position duringswinging of the harvester unit 15′ out from one side of the tractor 16′or the other. Depending on the materials of construction, thisembodiment may encounter slightly more flexing during use than thehitching arm of the previous embodiment, the total amount of flexingbeing about 0.3 m (1 foot) between the opposite ends, and so this degreeof flexing must be accommodated by the mechanical drive line 45′. Thiscan best be done by providing U-joints at the points where the driveline bends to follow the shape of the hitching arm, and also byproviding slip joints (splined telescopic sections) within the drivelineitself to accommodate lengthening and shortening actions of the line. Asa alternative to using U-joints for this purpose, it is also possible touse gearbox designs to achieve the required change of angle. A suitablegearbox design is shown in enlarged partial section in FIG. 8A, whichshows the driveline 45′ at the junction of arm sections 36′ and 39′. Thegearbox 801 consists of a housing 802 containing mutually-meshingrotatable beveled gears 803 and 804. The lowermost gear 804 is attachedto driveline section 47′ for rotation therewith and the uppermost gearis attached to driveline section 48′ for rotation therewith. The angleat which the gears are mutually arranged creates the change of directionof the driveline 45′ as it passes through the gearbox 801. A smalldegree of angular misalignment of the gears 803 and 804 is possible toaccommodate flexing, and more is permitted by the presence of constantvelocity joint 805 on one side of the gearbox and a slip joint 806 onthe other side. The gearbox must be strong enough to transmit the powerprovided to the driveline 45′ without distortion or overheating.

At the point of attachment of the hitching arm 35′ to the tractor 16′, aball joint 807 is provided to allow sharp turns, and a gearbox 808 maybe bolted to the tractor body.

In this embodiment, the hitching arm 35′ is attached to the harvestingunit 15′ at pivot 75′ which is placed no more than about 1.2 m (4 feet)in front of the rotational axis of the wheels 32′. This positioning isimportant for two reasons. Firstly, the close proximity of the pivot 75′to the wheels means that easier turning of the harvesting unit by thehydraulic cylinders 72′ and 73′ (See FIG. 8C) can be achieved. Secondly,the centre of gravity of the harvesting unit is slightly to the front ofthe wheels when the unit is empty, but moves rearwardly of the wheels asthe unit is filled during harvesting. This reduces the downward force onthe hitching arm and allows the hitching arm to be of a lighter designthan would otherwise be the case.

In this embodiment, the hydraulic lines from the tractor 16′ to theharvesting unit 15′ preferably follow the outside of the hitching arm35′ (rather than run through the hollow interior) for easier servicing,and the clearance of the cylinder can be adjusted from inside thetractor (along with all of the other hydraulic functions, preferablyusing a single-handed joystick design).

The harvesting unit 15′ of FIG. 8 differs from the harvesting unit 15previously described in several respects, as described in the following.

Firstly, instead of equipping the floor of the tank 33′ with a series ofparallel augers, as in the previous embodiment, in order to move thecollected graff towards the rear of the tank, a “live floor” 810 isprovided, i.e. an endless belt made up, for example, of mutually spacedtransverse slats driven by chains. This makes use of the principalmentioned earlier that graff may be moved by moving or removing theentire lowermost layer of a body of the graff, i.e. a lowermost layerthat extends completely across the width of the body of graff—in thiscase substantially the entire width of the tank 33′. In the previousembodiment, the intention was to deliver the graff as quickly aspossible to a large rear well 96 positioned at the rear of the tank 33from which the graff can be augered out as shown in FIG. 7D. In thissecond embodiment, the approach taken to graff removal is different.Instead of the large well 96, the tank 33′ is provided with a shallowtransverse well or channel 96′ enclosing a quite large (e.g. 50 to 60 cm(20 or 24 inches)) generally horizontal transverse auger 820 oralternatively a conveyor belt). The live floor 810 slopes upwardly tothe rear and thus the bulk of the body of collected graff tends toremain towards the front of the tank 33′ and the movement of the livefloor feeds a constant supply of graff into the channel 96′ when theauger is operated, thus reducing the risk that binding will take placeabove the auger, or blockage of the channel 96′ will occur.

The slats circulate around a plate 811 acting as a false floor of thetank and the slats themselves may be provided with flexible strips atthe front to provide a sweeping action over the false floor. The chains812 used to drive the slats (generally there are at least 2 andpreferably 3 parallel chains) provide an open structure that isself-cleaning, as it moves around the false floor. An alternativepossibility would be to use a flexible (e.g. rubber) conveyor beltinstead of the slats and chains, but material tends to build upunderneath such arrangements, so they are usable but no preferred.

The transverse auger 820 in the channel 96′ feeds a side-mounted hingedenclosed conveyor 815 or chute that is used to transfer the collectedgraff to an adjacent vehicle (not shown). The fact that the conveyor 815is hinged means that it can be raised or lowered to a point just abovethe vehicle box. A conveyor is used rather than an auger to providebodily transport of the graff supplied by the auger to prevent bindingand blockage. The arrangement also allows the tank to be emptiedquickly, e.g. within about 3 minutes or less.

A pair of augers 817 and 818 are provided at the top of the tank 33′ inorder to level the pile of graff (not shown) collected in the tank.These help to move the body of collected graff towards the rear of thetank. A sensor (not shown) is provided to indicate when the tank 33′ isfull so that graff does not overflow into and build up above the channel96′ before the auger 820 can be operated to begin removal of the grafffrom the tank. Such overfilling could promote binding and blockage. Theharvesting is interrupted when the sensor indicates that the tank isfull and emptying commences, assuming that emptying is not being carriedout simultaneously with harvesting (i.e. into a moving accompanyingvehicle).

In this embodiment, the tank may be made larger than the previousembodiment and the slope of side walls 28′ and 29′ is made a minimum of60°. The interior of the tank is again coated with low friction paint.The increased capacity may be obtained by increasing the height of theunit to 4.25 m (14 feet) and increasing its length (e.g. byapproximately 1.5 m (5 feet)). This may result in a tank 33′ having avolume of approximately 31.8 m³ (1120 cubic feet). While the tank 33′ isgenerally made of sheet metal, such as steel, the tank may,alternatively, be made of plastic material as the graff load is lightdespite the large volume.

Cleaning Mill

To further improve the efficiency and effectiveness of the harvestingmethod, an improved cleaning mill 20 (often referred to as a yard plant)has been produced.

The cleaning mill 20 is illustrated in perspective view in FIG. 9, fromwhich it can be seen that the mill consists of several main parts,namely a drive-in graff receiving unit 21 (which acts as an openreceptacle for the graff delivered by a vehicle) and graff conveyor 100,an aspirator 101 for removing chaff and light material from the graff, amillings collection unit 102, a screening unit 103, and a rolling mill104. The aspirator 101 is powered by a Written Pole motor 105, oralternatively a diesel motor, and the mill is controlled by a computermodule 106 (PLC).

Graff is delivered to the cleaning mill 20 directly from the field by atruck 17 (see FIG. 1). In the past, attempts were made to pour the graffthrough a small door positioned in the rear wall or gate of the truckbox in the same manner that grain is delivered to a grain storage area.However, as noted above, graff does not flow in the same way as grain,and once deposited in a pile, it is difficult to pick up and convey tothe cleaning mill. To overcome this problem, the illustrated cleaningmill has a drive-in graff receiving unit 21 that allows a truck to backdirectly into the receptacle (as suggested by the tire tracks 107 shownin FIG. 9) and to dump the graff by unhooking the rear gate and raisingthe truck box (as illustrated in FIG. 1).

The graff receiving unit 21 is a grain receptacle in the form of a flatbox 108 having a slightly ramped bottom wall 109 and two longitudinalside walls 110, but no end walls. The unit is aligned with the moresteeply upwardly ramped graff feeding apparatus or conveyor 100 formingan inclined surface. FIGS. 11 and 12 are side views showing thereceiving unit in a receiving position (FIG. 11) awaiting a graffdelivery, and in the upturned operational position (FIG. 12), in whichthe receiving unit acts as a chute so that graff is urged onto thebottom end of the graff conveyor 100. The tilting of the receiving unitis controlled by hydraulic cylinders on each side of the unit (althoughonly one is shown in FIGS. 11 and 12).

In the case of the graff conveyor, the ramped surface 113 is providedwith a rotating drag chain conveyor 112 that moves up the ramp andcarries graff to the upper end 114. A rotating delivery roller 115 atthe upper end of the drag chain conveyor functions to beat back graffcoming up the conveyor and equalize out the graff across the width ofthe box (usually 10 feet wide) so that only a 4 to 8 cm (1.5 inch to 3inch) mat of graff proceeds to the top 114 of the graff receiving unit.The thickness of the mat is determined by the adjustable distance fromthe drag chain 112 to the roller 115. The roller is positioned a shortdistance (a few centimeters) above the upper end of the ramped surface113, and is provided with projecting teeth 116 spaced along and aroundthe circumference of the roller. The delivery roller is rotated rapidlyby a motor (not shown) and, as noted, feeds a “mat” or carpet of graff(i.e. a continuous strip of even width and thickness) into an upperentrance 117 of the aspirator unit 101 (see FIG. 9). The graff conveyor100 serves the purpose of lifting the graff from ground level to anelevated position from which it may be subjected to aspiration as itfalls vertically back to ground level within the cleaning mill. A secondfunction of the drag chain conveyor 112 is to meter (by changing thespeed of the conveyor driven by a variable speed motor) the correctvolume of graff delivered to the top 114 of the receiving unit and intothe aspirator 101. Therefore, by varying the speed of the conveyor andby varying the distance between it and the roller 115, acceptableamounts of graff can be metered into the aspirator 101. It is importantthat the entire width of the aspirator (3 m (10 feet) for 91,000 liters(2,500 bushels) per hour) is matched to the width of the receiving unitto facilitate the continuous material flow capability of the entiremachine.

The aspirator 101 is shown in greater detail and in isolation from theother equipment in FIGS. 13A, 13B and 13C. The mat or carpet of graffpasses through an entrance 117 to the aspirator unit and directlyencounters an aspirator reel 300. The reel is shown in isolation in FIG.13C and it will be seen that a number of rubber cogs 301 (three inchesin height) are arranged along the surface of the reel with a slighttwist (preferably about 10°) in the axial direction to facilitate entryof the graff into the aspirator. The rubber cogs 301 form an air sealpreventing air under pressure in the aspirator 101 from escaping throughthe inlet 117. It will be seen from FIG. 13A that there is no free spacewithin the entrance 117 to allow graff to settle and clog the apparatus.Once graff passes through the entrance 117, it is immediately taken upby the reel which delivers it to the aspirator. As a stream 118 of grafffalls vertically through the aspirator, it is subjected to a lateralairflow 119 that impinges on one side (the front) of the stream andpasses through to the other side carrying away chaff and other lightmaterials. The aspirator has six drop zones defined by baffles 120. Theair flow through each drop zone is controlled by a manually adjustabledamper 121 at the drop zone's inlet. In each drop zone, the air streampasses through the falling graff.

The airflow 119 is created by a fan 122 which moves air along a lowerduct 123 to a front end of the aspirator, and then, after passingthrough the falling stream of graff 118, returns the air (and entrainedchaff and light materials) through an upper duct 124. If too much air isentering into the front of the aspirator 101, air can be bled offdirectly into the return air flow by a manually operated gate 302. Acentrifugal (cyclone) separator 125 removes the chaff and lightmaterials from the air flow before the air returns to the fan 122. Theseparated mixture of chaff and light materials (referred to as“millings”) is conveyed by a material conveying fan 126 (see FIG. 13B)to a conveying tube 127 and may be delivered to a suitable storage pile,container, or vehicle via a pipe 128 (see FIG. 13D) attached to theconveying tube 127. The pipe 128 (which may be as long as 15 to 21 m (50to 70 feet)) has a small cyclone unit 129 at its remote end acting as adecelerator for the millings to prevent widespread distribution of thislight material, and allowing it to collect into a pile 135.

The operation of the separator cyclone 125 is governed by the fan 122(see FIG. 13A) operating at a volume of about 340 m³ (12,000 cubic feet)per minute (for 91,000 liters (2,500 bushels) of graff per hourthroughput). The fan forces air through the aspirator 101 and along duct124 to the separator 125. The millings material contained in the airflowupon reaching the separator clings to the outer wall of the separator bycentrifugal force and moves to a final discharge portal 303. Thedischarge through portal 303 is assisted by air equalization tube 304shown in FIG. 9 and by the discharge fan 126 shown in FIG. 13B. Withinthe separator 125, clean air in the middle of the unit is returned tothe fan 122 by duct 305 shown in FIG. 13B. The cleaned air is driven bythe fan 122 and returns to the aspirator 101 via ducting 123 to a frontside of the aspirator. The ducting forms a closed loop for the air torecirculate between the centrifugal separator 125 and the aspirator 101.Dust build-up within the closed loop is avoided by the introduction ofmake-up air from the rolling mill 172 and screening unit 103.

The heavy material 130 (aspirated graff, which contains the grain andweed seeds, etc.) collects at the bottom of the aspirator 101 and isremoved by a horizontal cross auger 131, then raised by paddle elevator132 (see FIG. 9) to a drop tube 133, from which it falls into thescreening unit 103 for separation into the desired cleaned grain productand other a secondary product comprising the remaining organic material.

The screening unit 103 is shown in detail in the perspective view ofFIG. 10. The material delivered from drop tube 133 falls into a split(bi-directional) leveling auger 140 positioned at the upper end of thescreening unit which serves to distribute the material evenly across thescreens. The unit consists of an open framework 141, retaining a numberof downwardly sloping oscillating screens 142 arranged in two groups or“shoes.” The opening size of the screens decreases from the uppermost tothe lowermost screen, so that larger particles are collected on theupper screens and smaller particles descend to the lower screens. Aseparation of the aspirated graff based on particle size is thusobtained. The top shoe 143, contains three scalping screens 144, 145 and146, through which the grain passes and large material is removed. Thefirst screen 144 of this shoe directs stones and larger debris to ahopper 307 from which it exits the machine. The second and thirdscreens, through which grain kernels drop, direct larger crop materialto a trough 147. From the top shoe, the grain flow is divided anddropped onto two screens on the bottom shoe 148. The bottom shoe 148contains two sets of three inclined, oscillating sizing screens. Thegrain passes over the screens while the “screenings” (weed seeds, smallkernels, etc.) pass through and are gathered in a trough below thescreen. The grain then drops through a plenum 160 with a cross-flow airstream where dust is removed from the grain and conveyed through a dustdelivery tube 150. The grain falls into a cross-conveyor 161, whichdelivers the grain 25 into a hopper 165. From the hopper, the grain isconveyed to storage.

Screenings from the two top shoe screens and the six bottom shoe screensare gathered in troughs and routed via drop tubes to the bottom shoesscreenings collection trough. From this trough, the screenings aredelivered into a paddle elevator 170, which lifts the screenings to adrop tube 171, from which the screenings fall into an intake hopper of arolling mill 172 (see FIG. 9) where the screenings are rolled. From thebottom of the rolling mill 172, air is drawn along with the rolledscreenings into a duct 308 connected to an intake 309 of the cycloneseparator 102. Within the separator 125, the rolled screenings from themill 172 are re-combined with the light material from the aspirator 101and the dust from the plenum 160 of the screening unit 103 delivered viadust delivery tube 150.

As already noted, solids (millings) separated from the air by separator125 are drawn by a portion of the air through a duct 173 into amaterial-conveying fan 126 (FIG. 13B). The fan helps to remove themillings and air from the separator 125 in a continuous manner withoutdisrupting the centrifugal separation effect within the separator. Thishas proven to be in improvement on the usual air lock provided forremoval of solids from a separator. The fan 125 also makes it possibleto project the millings a considerable distance from the machine viaconveying tube 127 and pipe 128 to the small cyclone decelerator 129.The millings, which consist of just about all of the organic matter fromthe graff other than the grain kernels are dropped into a pile 135 forstorage. Weed seeds in this material have been passed through therolling mill 172 and thus are no longer viable (i.e. they are inert).Moreover, small screened grain kernels are also crushed, making themmore digestible for cattle. The collected millings are therefore avaluable product that may be used as animal feed or for other purposes.Despite this rolling step, only a single material (other than thecleaned grain) is discharged from the mill because of the recirculationof rolled material to the intake of the separator unit where it is mixedwith light materials from the aspirator. Of note is also the final airbath applied to the cleaned grain just before it is discharged from themill. This air bath removes fine dust that is also recirculated to theintake of the separator 125.

Of course, if desired, the rolled material and/or the dust from the airbath need not be returned to the separator, but could be dischargedindependently merely by rerouting the indicated piping. The materialfrom the screens (screenings) is by itself a high protein feed material.

A particular advantage of the cleaning mill is that, if desired, it canbe operated automatically, essentially without an operator. Computercontrol ensures normal operation of the mill at all times.

An alternative embodiment of the cleaning mill is shown in FIGS. 14 and15. In this embodiment, the graff receiving unit 21′ (which forms anopen receptacle for the graff) and the graff conveyor 100′ areessentially the same as in the previous embodiment and allow graff to bedeposited as a full load from a truck by upending the truck box, dumpingthe graff load, and delivered in a constant stream to a laterallyelongated upper inlet 117′ of the cleaning mill without binding orblocking and without the need for intermediate storage. However, uponpassing through the inlet 117′, the graff enters a transverse channel900 containing a cross-directed gathering auger 901 (which preferablyhas a diameter of 43 cm (17 inch)). The purpose of this auger is toreduce the width of the graff flow from that of the graff conveyor 100′(approximately 3 m or 3.3 m (10 or 11 feet)) to that of the width of thecleaning mill itself, which is somewhat narrower (approximately 143 cm(56 inches)). By this means, the both the cleaning mill and the conveyormay be designed to have optimal widths for their intended functions,even though those widths may differ.

In this embodiment, the screening unit 103 of the previous embodiment isincorporated into the main body 905 of the cleaning mill 20′. This makesthe cleaning mill more compact and easier to operate. As shown insimplified schematic form in FIG. 14, upon leaving the transversechannel 900 at the central opening 975, the graff falls onto a grain pan907 provided with a reciprocating action that tends to stratify thegraff into components of different density and levels the graff into aneven carpet 908 having a width of 0.6 to 1.2 m (2 to 4 feet). The grainpan moves the graff forwards until it falls onto a cleaning shoe 909.The cleaning show includes an upper chaffer screen 910 and a lower grainsieve 911 (both of which are of adjustable mesh size) that arereciprocated back and forth in an opposed motion. A short extensionsieve 912 is also provided at the distant end of the chaffer 910. Thiscan be adjusted independently of the chaffer, and can be raised at anangle to slow down the flow of material, if desired. The chaffer andgrain sieve each preferably have a surface area of about 1.7 m² (17.9sq. ft.). The mesh size of the chaffer is larger than that of the grainsieve. As the graff passes through the shoe 909, large chaff, stalks,cut heads and stones are separated mainly by the chaffer 910 and thenintermediate contents (e.g. weed seeds, small chaff, stalk parts, etc.),are separated at the grain sieve 911. Essentially only grain 915 itselfpasses through the grain sieve 911 and falls to a collection pan 916that has sloping front and rear walls directing the grain to a centraltrough 917 for removal by a cross auger 918 through a grain exit 919.

As the graff is separated into its components in this way, air is blownupwardly and outwardly through the shoe 909 as indicated by arrows A.This air flow suspends essentially all of the graff components exceptthe grain and heavy objects such as stones. In fact, as the graff dropsonto the shoe 909 from the grain pan 907, it encounters a blast of airforceful enough to blow away essentially everything but clean grainkernels of the desired size (and heavy objects, such as stones). Thisreduces the amount of separation required to be carried out by the shoe911 itself. Both the suspended chaff and the heavy objects proceed to acyclone separating unit 920. The suspended chaff is carried by the airflow, whereas the heavy objects are moved by the reciprocating action ofthe shoe sieves into the inlet 921 of the cyclone unit.

The airflow is created by a fan 925 (e.g. a 16.5 kW (22 hp) centrifugalfan creating a throughput of 400 m³/min (4,000 cubic feet/minute))positioned within the cleaning mill beneath the graff conveyor 100′. Thefan directs air into conduit 926 leading to the cleaning shoe 909, butan adjustable diverter 927 is provided upstream of the shoe to direct aportion of the air into a bypass conduit 930 as indicated by arrows B.The air from the bypass 930 nevertheless also enters the cyclone unit920 with the air that has passed through the cleaning shoe 909. Thediverter allows the airflow A through the shoe to be made appropriatefor cleaning the graff (designed to blow away everything below kernelremoval) while still allowing a high rate of airflow through the cycloneunit 920. The diverter 927 may be either manually adjustable orautomatically controlled based on the rate of feed of graff into thecleaning mill.

A stone cleanout door 932 is provided at the bottom of the cyclone unit920 to allow stones and other large or heavy objects to be removedperiodically from the bottom of the cyclone unit where they tend tocollect as they are not removed by the airflow.

The cyclone unit 920, by virtue of the spiral flow of air there throughand the density of the suspended chaff, causes the suspended chaff tocongregate around the inside wall 935 of the unit so that clean air thatis substantially free of chaff and other solids may exit the unitthrough a central opening 936. The chaff, propelled by a further flow ofair, exits a chaff delivery port 937 located at an outside lower regionof the cyclone unit. The clean air is recirculated directly to the fan925 via ducting 940 (see FIG. 15), although a certain amount of cleanair from the outside may be introduced into the recirculated air, e.g.through an elongated slot provided adjacent to the graff entrance 117′,to replace air escaping with the chaff and to reduce the build-up ofdust (about 90% recirculation is usual).

The solids exiting chaff delivery port 919 contains chaff proper, weedseeds, unthreshed heads, and small grain kernels. As shown in FIG. 15,this is conveyed through ducting 950 to a high speed centrifugalmaterial-conveying fan 951 provided with paddle-like blades. The fan hasa hammering, impacting or chopping effect that reduces the size of largeitems and tends to crack, nick or crush weed seeds and small grainkernels (thus making them less liable to germinate). The fan ispreferably operated at a speed of about 3293 rpm, giving the fan avelocity at its blade tips of about 440 km/hr and a throughput of about57 m³/min (2000 cubic feet/minute). Obviously, variations (e.g. ±10%) ofthese speeds and velocities may be employed, provided the desiredmaterial conveying and seed cracking effects are obtained. The materialexiting the fan is then conveyed through tubing 952 to a desiredlocation where it is discharged to form an open pile (not shown) (or itmay, if desired, be discharged into a silo or other form of container,however the crushed millings adhere to themselves and cake together sothe material tends not to blow away from an open pile). The millingsform a good quality animal feed similar in nutrient content to hay. Thefan 951 and tubing 952 may convey the solids up to a distance of about60 m (200 feet) from the cleaning mill, depending upon the power of thefan 951. The fan 951 acts to both convey the separated solids and tocrush them. It acts at a fast rate of throughput and is rarely subjectto blockage, plugging or failure for other reasons. This is all achievedat a reasonable cost in power to operate the fan.

In a preferred form of this embodiment, as shown, a single motor 955 isused to drive both the air fan 925 and the material-conveying fan 951.This is preferably a written pole (single phase) electric motor of 30 to37.5 kW (40-50 hp). Approximately eight additional small electric motors(of approximately 1.5-2.25 kW (2-3 hp) each) are required for thecomplete operation of the cleaning mill. Advantageously, all thesemotors may be designed to operate on single phase power that is mostreadily available on farms and in remote areas.

The cleaned grain exits the grain delivery port (propelled by thepositive air pressure in the cleaning mill or extracted by an auger) andis delivered by an auger to a storage container (e.g. one or moresilos-not shown).

The cleaning mill of this embodiment maintains a constant recirculationof air and a constant stream of graff into the mill and constant streamsof cleaned grain and the remaining constituents from the mill. Theillustrated unit is capable of processing 91,000 liters (2500 bushels)of graff per hour. The receiving unit 21′ is capable of holding at least27,000 liters (750 bushels) of graff. A single load from a truck cantherefore be processed in about 20 minutes.

The mill can be essentially left to operate without supervision. Thetruck operator can use a remote control device to lower the receivingunit as the truck approaches, dump the load of graff, and then set thecleaning mill in operation and leave for another load. The mill may becomputer controlled to raise the receiving unit in stages to feed thegraff conveyor appropriately, and to run all of the fans and motorsuntil a sensor indicates that all of the graff has been processed. Theunit may then shut itself off automatically, awaiting the next load.

What I claim is:
 1. A method of harvesting and cleaning a plant crop,wherein the crop is cut from a field area and threshed in a mobileharvesting unit to produce stalks that are returned to the field areaand “graff”, a mixture including grain, chaff and weed seeds, which iscollected within the harvesting unit; the collected graff is transferredperiodically from the harvesting unit to at least one vehicle andtransported by said at least one vehicle to a cleaning mill, and thegraff is cleaned by the cleaning mill to produce a cleaned grain productand “millings”, a mixture including chaff and weed seeds; wherein saidgraff, after harvesting of said crop, is transferred directly from saidharvesting unit to said vehicle to form a vehicle load of said graff,which load is transported to the cleaning mill, the vehicle load isdumped en masse directly from said vehicle into an integral graffreceiving unit of said cleaning mill, and the dumped load is then feddirectly and continuously by the receiving unit into the cleaning millfor separation of grain from the graff, thereby avoiding temporarystorage of said graff subsequently to unloading of said vehicle andprior to cleaning of said graff by said cleaning mill.
 2. The method ofclaim 1, wherein the graff is fed from the dumped load to a graffentrance of the cleaning mill by removing graff from a lowermost layerof the dumped load in said graff receiving unit over substantially theentire transverse width of said dumped load to avoid interruptions ofgraff feed caused by binding, blocking, or bridging of the graff withinthe load.
 3. The method of claim 2, wherein the graff is removed fromsaid lowermost layer of the dumped load by positioning the load on asurface and moving the surface, or elements extending across thesurface, beneath the load.
 4. The method of claim 1, wherein saidtemporary storage of the graff prior to cleaning is also avoided, atleast in part, by making the graff holding capacity of the harvestingunit the same as or smaller than the graff holding capacity of said atleast one vehicle, so that all of said graff collected in saidharvesting unit is transferred in a single emptying operation to said atleast one vehicle.
 5. The method of claim 4, wherein the capacity of theharvesting unit is made substantially the same as the capacity of the atleast one vehicle.
 6. The method of claim 1, wherein said graff iscleaned in the cleaning mill at a rate that is the same as or higherthan the rate of graff output from the field area.
 7. The method ofclaim 6, wherein the rate of cleaning of the graff by the cleaning millis substantially the same as the rate of graff output from the fieldarea.
 8. The method of claim 1, wherein said at least one vehicle isoperated such that graff is conveyed from the harvesting unit to thecleaning mill at a rate sufficient to avoid substantial waiting periodsbetween emptying operations of said harvester unit.
 9. The method ofclaim 1, wherein the graff is transported from the harvesting unit tothe cleaning mill in a single vehicle travelling continually back andforth between the harvesting unit and the cleaning mill.
 10. A systemfor harvesting and cleaning a plant crop, which includes a harvestingunit for cutting a crop from a field area and threshing the cut crop toproduce stalks that are returned to the field area and “graff”, amixture including grain, chaff and weed seeds, which is collected withinthe harvesting unit; at least one vehicle for receiving collected grafffrom the harvester unit when the harvesting unit is at least partiallyfull, and for transporting the graff to a cleaning mill; and a cleaningmill located in a yard area remote from the field area, for cleaning thegraff to produce a cleaned grain product and “millings”, a mixtureincluding chaff and weed seeds; wherein said cleaning mill has anintegral graff receiving unit adapted to feed a load of graff dumpedfrom said vehicle en masse into said receiving unit directly andcontinuously into said cleaning mill, and wherein the system excludesany device for temporary storage of the graff prior to cleaning of thegraff in the cleaning mill other than said harvester unit, said vehicleand said receiving unit of said cleaning mill.
 11. The system of claim10, wherein the feeding graff receiving unit removes graff from alowermost layer of the dumped graff load over substantially the entiretransverse width of the dumped load, thereby avoiding interruptionscaused by binding, blocking or bridging of the graff within the load.12. The system of claim 11, wherein the feeding apparatus includes asurface on which the load is positioned, and means for moving thesurface, or elements extending transversely across the surface, toconvey graff from the load to the graff entrance of the cleaning mill.13. The system of claim 10, wherein the harvesting unit has a graffholding capacity that is the same as or smaller than the graff holdingcapacity of said at least one vehicle used for graff transportation. 14.The system of claim 10, wherein the cleaning mill operates at a rate ofcleaning of the graff that is the same as or higher than the rate ofgraff output from the field area.
 15. The system of claim 10, whereinsaid at least on vehicle is operated at a rate sufficient to conveygraff from the harvesting unit to the cleaning mill while avoidingsubstantial waiting periods between emptying operations of saidharvesting unit.
 16. The system of claim 15, wherein a single vehicle isprovided for conveying graff between the harvesting unit and thecleaning mill.
 17. A method of harvesting and cleaning a plant crop,wherein the crop is cut from a field area and threshed in a mobileharvesting unit to produce stalks that are returned to the field areaand “graff”, a mixture including grain, chaff and weed seeds, which iscollected within the harvesting unit; the collected graff is transferredperiodically from the harvesting unit to at least one vehicle andtransported by said at least one vehicle to a cleaning mill, and thegraff is cleaned by the cleaning mill to produce a cleaned grain productand “millings”, a mixture including chaff and weed seeds; wherein saidgraff, after harvesting of said crop, is transferred directly from saidharvesting unit to said vehicle to form a vehicle load of said graff,which load is transported to the cleaning mill, the vehicle load isdumped en masse directly from said vehicle into an integral graffreceiving unit of said cleaning mill, and the dumped load is then feddirectly and continuously by the receiving unit into the cleaning millas a continuous strip having a width substantially the same as that ofsaid dumped load, before a further load of graff is dumped into saidreceiving unit from a vehicle, thereby avoiding temporary storage ofsaid graff subsequently to unloading of said vehicle and prior tocleaning of said graff by said cleaning mill.